Surgical stapling device

ABSTRACT

A surgical stapling device is disclosed for performing circular anastomoses. The surgical stapling device includes a handle portion, an elongated body portion and a head portion including an anvil assembly and a shell assembly. A removable trocar for attachment to the anvil assembly is also disclosed which includes a rib positioned proximally of a mounting projection. The rib is positioned to align the mounting projection with associated engagement structure of the anvil assembly.

This application is a divisional application of U.S. patent applicationSer. No. 11/515,660, filed Sep. 5, 2006, which is a continuation-in-partof U.S. patent application Ser. No. 10/528,975, filed Mar. 23, 2005, nowU.S. Pat. No. 7,303,106, which claims the benefit of and priority to PCTApplication Serial No. PCT/US03/31638, filed Oct. 6, 2003, which claimsthe benefit of and priority to U.S. Provisional Application Ser. No.60/416,055, filed Oct. 4, 2002, the entire contents of all of whichbeing incorporated by reference herein. U.S. application Ser. No.11/515,660 also claims the benefit of and priority to U.S. ProvisionalApplication Ser. No. 60/714,141, filed Sep. 2, 2005, the entire contentsof which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present disclosure relates generally to a surgical stapling devicefor applying surgical staples to body tissue. More particularly, thepresent disclosure relates to a surgical stapling device suitable forperforming circular anastomosis of hollow tissue organs.

2. Background to Related Art

Anastomosis is the surgical joining of separate hollow organ sections.Typically, an anastomosis procedure follows surgery in which a diseasedor defective section of hollow tissue is removed and the remaining endsections are to be joined. Depending on the desired anastomosisprocedure, the end sections may be joined by either circular,end-to-side or side-to-side organ reconstruction methods.

In a circular anastomosis procedure, the two ends of the organ sectionsare joined by means of a stapling instrument which drives a circulararray of staples through the end section of each organ section andsimultaneously cores any tissue interior of the driven circular array ofstaples to free the tubular passage. Examples of instruments forperforming circular anastomosis of hollow organs are described in U.S.Pat. Nos. 6,053,390, 5,588,579, 5,119,983, 5,005,749, 4,646,745,4,576,167, and 4,473,077, each of which is incorporated herein in itsentirety by reference. Typically, these instruments include an elongatedshaft having a handle portion at a proximal end to actuate theinstrument and a staple holding component disposed at a distal end. Ananvil assembly including an anvil rod with attached anvil head ismounted to the distal end adjacent the staple holding component. Opposedend portions of tissue of the organs to be stapled are clamped betweenthe anvil head and the staple holding component. The clamped tissue isstapled by driving one or more staples from the staple holding componentso that the ends of the staples pass through the tissue and are deformedby the anvil head.

In use, the staple holding component and anvil assembly are positionedwithin opposed sections of the organs to be joined and are not visibleto the surgeon. Typically, an indicator is provided on the staplingdevice which is visible to the surgeon to identify when the anvilassembly and staple holding portion have been sufficiently approximatedsuch that the device is in a fire-ready position. Conventionalindicators include indicia which is moved to a position visible to asurgeon when the device has been approximated. Such indicia is sometimesdifficult to view.

Accordingly, a need exists for a stapling device with anapproximation/fire-ready indicator which prominently displays indiciawhich is easily viewable by a surgeon.

SUMMARY

In accordance with the present disclosure, a surgical stapling device isdisclosed which includes a handle assembly having a stationary handle, afiring trigger and a rotatable approximation knob. An elongated bodyportion extends distally from the handle assembly. A head portionincluding an anvil assembly and a shell assembly is positioned at thedistal end of the body portion. The shell assembly supports a pluralityof staples. An approximation mechanism includes the approximation knob,a drive screw and an anvil retainer. The anvil retainer is operablyconnected to the drive screw. The drive screw includes a helical channelhaving a first pitch. The approximation knob is operably connected to apin which is positioned within the helical channel such that rotation ofthe approximation knob effects linear movement of the drive screw andanvil retainer between a first advanced position and a second retractedposition. A firing mechanism includes the firing trigger and a pusherlink. The firing trigger is operably connected to the pusher link suchthat operation of the firing trigger ejects the plurality of staplesfrom the shell assembly. The anvil assembly includes an anvil center rodconfigured to releasably engage the anvil retainer. The approximationmechanism is operable to retract engaged portions of the anvil centerrod and the anvil retainer within the shell assembly to lock the anvilcenter rod to the anvil retainer.

In one embodiment, the helical channel of the screw includes a dwellportion having a second pitch which is smaller than the first pitch. Thedwell portion is positioned along the helical channel to provide atactile indication to a surgeon that the anvil retainer has beenadvanced to a third position between the first advanced position and thesecond retracted position. In one embodiment, the third position is theposition in which the anvil assembly is no longer locked to the anvilretainer assembly.

In one embodiment, the anvil center rod includes a plurality of flexiblearms which are positioned to flex over and engage an annular protrusionformed about the anvil retainer. The shell assembly can include an innerguide portion having a rigid bushing dimensioned to slidably receive theengaged portions of the anvil center rod and the anvil retainer. Therigid bushing is dimensioned to provide lateral support for the flexiblearms of the anvil center rod to prevent disengagement of the anvilcenter rod from the anvil retainer.

In one embodiment, the dwell portion of the helical channel isdimensioned to permit between about ½ to about ¾ of a turn of theapproximation knob without effecting substantially any linear movementof the screw.

In one embodiment, the surgical stapling device includes a pivotabletrigger lock supported on the handle assembly. The pivotable triggerlock is movable from a first position to prevent actuation of the firingtrigger to a second position to permit actuation of the firing trigger.The firing trigger can include a pivotable member. The pivotable memberincludes first and second spaced abutments. A tip of the pivotabletrigger lock is positioned between the spaced abutments when thepivotable trigger lock is in its first position. In one embodiment, thetip of the pivotable trigger lock includes a flexible tab which ispositioned to engage the pivotable member between the spaced abutmentsto prevent rattling of the pivotable trigger between the spacedabutments.

A removable trocar for attachment to the center rod of an anvil assemblyis also disclosed. The removable trocar includes a body having aproximal end and a distal end, a trocar tip formed at the distal end ofthe body and a cantilevered arm extending along a longitudinal axis ofthe body. The cantilevered arm includes a distal end secured to the bodyand a proximal end having a protrusion formed thereon. In oneembodiment, the protrusion is dimensioned to be releasably receivedwithin an opening of an anvil center rod. The body also includes a ribextending proximally of the protrusion. The rib is dimensioned to slidebetween flexible arms of an anvil center rod to properly align theprojection with the opening of the anvil center rod.

The projection can include an angled proximal face. The cantilevered armcan include a distal tab which is positioned to facilitate deflection ofthe cantilevered arm to disengage the projection from an anvil centerrod. In one embodiment, the body includes at least one spline offsetfrom the rib. A throughbore can be provided in the body which isdimensioned to receive a suture.

BRIEF DESCRIPTION OF THE DRAWINGS

Various preferred embodiments of the presently disclosed surgicalstapling device are disclosed herein with reference to the drawingswherein:

FIG. 1 is a top side perspective view from the proximal end of thepresently disclosed surgical stapling device in the unapproximatedposition;

FIG. 2 is a top side perspective view from the distal end of thesurgical stapling device shown in FIG. 1;

FIG. 3 is a side perspective exploded view of the handle assembly of thesurgical stapling device shown in FIG. 1;

FIG. 3A is a top perspective view of the indicator of the handleassembly shown in FIG. 3;

FIG. 4 is a side perspective view from the top of the handle assembly ofthe surgical stapling device shown in FIG. 1 with a handle sectionremoved;

FIG. 5 is a side perspective view from the bottom of the handle assemblyof the surgical stapling device shown in FIG. 4;

FIG. 6 is a side perspective exploded view of the central body portionand distal head portion of the surgical stapling device shown in FIG. 1;

FIG. 7 is an enlarged side perspective of the anvil retainer and bandportions of the central body portion shown in FIG. 6;

FIG. 8 is a side perspective view of the screw and screw stop of theapproximation mechanism of the handle assembly shown in FIG. 5;

FIG. 9 is an enlarged view of the indicated area of detail shown in FIG.3;

FIG. 9A is a side perspective view from the top of the abutment memberof the handle assembly shown in FIG. 3;

FIG. 10 is a side perspective exploded view from the proximal end of theanvil assembly of the surgical stapling device shown in FIG. 1;

FIG. 11 is a side perspective view of the retaining clip of the anvilassembly shown in FIG. 10;

FIG. 12 is a side perspective view of the distal end of the center rodof the anvil assembly shown in FIG. 10 with a removable trocar fastenedthereto;

FIG. 13 is a side perspective view of the center rod and removabletrocar shown in FIG. 11 separated one from the other;

FIG. 14 is a side perspective view from the proximal end of the anvilassembly shown in FIG. 10 with the removable trocar attached thereto;

FIG. 15 is a side perspective view from the distal end of the anvilassembly shown in FIG. 14;

FIG. 16 is a side cross-sectional view taken through the retaining clipof the anvil assembly and removable trocar of the anvil assembly shownin FIG. 15;

FIG. 17 is an enlarged view of the indicated area of detail shown inFIG. 16;

FIG. 18 is a side cross-sectional view taken through the pivot member ofthe anvil head assembly of the anvil assembly shown in FIG. 15;

FIG. 19 is a side perspective view from the proximal end of the anvilassembly shown in FIG. 18 with the removable trocar removed;

FIG. 20 is a perspective, partial cutaway view from the distal end ofthe anvil assembly shown in FIG. 19, with the anvil head removed;

FIG. 21 is a side cross-sectional partial cutaway view of the distalportion of the anvil assembly shown in FIG. 19, with the anvil head inphantom;

FIG. 22 is a side perspective view from the bottom of the screw stop ofthe handle assembly shown in FIG. 3;

FIG. 23 is a bottom perspective view from the proximal end of the screwstop shown in FIG. 22;

FIG. 24 is a top perspective view of the cam adjustment member of thehandle assembly shown in FIG. 3;

FIG. 25 is a side view of the screw and screw stop of the handleassembly shown in FIG. 3 with the set screw and the cam adjustmentmember removed;

FIG. 26 is a side view of the screw and screw stop shown in FIG. 25 withthe set screw and cam adjustment member attached thereto;

FIG. 27 is a side view of the screw and screw stop shown in FIG. 26 withthe cam adjustment screw adjusted to increase the tissue gap;

FIG. 28 is a side view of the screw and screw stop shown in FIG. 26 withthe cam adjustment screw adjusted to decrease the tissue gap;

FIG. 29 is a top perspective view from the proximal end of the slidemember of the indicator mechanism of the handle assembly shown in FIG.3;

FIG. 30 is a bottom perspective view of the lockout member of the firelockout mechanism of the handle assembly shown in FIG. 3;

FIG. 31 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 1 with the anvil assembly removed;

FIG. 32 is a side enlarged view of the handle assembly of the surgicalstapling device shown in FIG. 31 with the handle sections removed;

FIG. 33 is an enlarged view of the indicated area of detail shown inFIG. 31;

FIG. 34 is an enlarged view of the indicated area of detail shown inFIG. 31;

FIG. 35 is a perspective view from the front of the distal end of thesurgical stapling device shown in FIG. 31 with the anvil assemblyremoved;

FIG. 36 is a perspective view from the front of the distal end of thesurgical stapling device shown in FIG. 35 with an anvil assemblyattached thereto;

FIG. 37 is a side cross-sectional view of the distal end of the surgicalstapling device shown in FIG. 36;

FIG. 38 is a side cross-sectional view of the surgical stapling deviceshown in FIG. 31 with the anvil assembly attached thereto;

FIG. 39 is a cross-sectional view taken along section lines 39-39 ofFIG. 38;

FIG. 40 is a cross-sectional view taken along section lines 40-40 ofFIG. 38;

FIG. 41 is a cross-sectional view taken along section lines 41-41 ofFIG. 38;

FIG. 42 is a cross-sectional view taken along section lines 42-42 ofFIG. 38;

FIG. 43 is a cross-sectional view taken along section lines 43-43 ofFIG. 38;

FIG. 44 is a cross-sectional view taken along section lines 44-44 ofFIG. 38;

FIG. 45 is a side perspective view of the surgical stapling device shownin FIG. 38 with the anvil assembly in an approximated position;

FIG. 46 is a side cross-sectional view of the distal end of the surgicalstapling device shown in FIG. 45;

FIG. 47 is a side enlarged view of the handle assembly of the surgicalstapling device shown in FIG. 45 with a handle section removed;

FIG. 48 is a side cross-sectional view of the handle assembly of thesurgical stapling device shown in FIG. 45;

FIG. 49 is a top horizontal cross-sectional view of a portion of thehandle assembly of the surgical stapling device shown in FIG. 45;

FIG. 50 is a side view of a portion of the handle assembly of thesurgical stapler shown in FIG. 45 with the handle sections removed;

FIG. 51 is a side cross-sectional view of a portion of the handleassembly of the surgical stapling device shown in FIG. 45 after thefiring trigger has been actuated;

FIG. 52 is a side cross-sectional view of the distal end of the surgicalstapling device shown in FIG. 45 after the firing trigger has beenactuated;

FIG. 53 is a side view of the handle assembly shown in FIG. 51 with thehandle sections removed;

FIG. 54 is an enlarged view of the firing link extension engaging theabutment member of the tactile indicator mechanism of the handleassembly shown in FIG. 53;

FIG. 55 is a side cross-sectional view of the distal portion of theanvil assembly of the surgical stapling device shown in FIG. 52;

FIG. 56 is a side cross-sectional view of the distal portion of theanvil assembly shown in FIG. 55 with a portion of the anvil headassembly in phantom;

FIG. 57 is a side view of the surgical stapling device shown in FIG. 45after the anvil assembly and cartridge assembly have been unapproximateda distance sufficient to permit the anvil head assembly to pivot on theanvil center rod;

FIG. 58 is an enlarged view of the abutment member of the tactileindicator mechanism of the handle assembly shown in FIG. 53 (duringunapproximation of the anvil and cartridge assemblies) with the wing ofthe screw stop, shown in phantom, in engagement with the abutmentmember;

FIG. 59 is a side cross-sectional view of the anvil assembly shown inFIG. 56 as the anvil head assembly begins to tilt;

FIG. 60 is a side cross-sectional view of the anvil assembly shown inFIG. 59 with the anvil assembly tilted; and

FIG. 61 is a side view of the surgical stapling device shown in FIG. 45with the anvil head assembly unapproximated and tilted.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the presently disclosed surgical staplingdevice will now be described in detail with reference to the drawings inwhich like reference numerals designate identical or correspondingelements in each of the several views.

Throughout this description, the term “proximal” will refer to theportion of the instrument closest to the operator and the term “distal”will refer to the portion of the instrument furthest from the operator.

FIGS. 1 and 2 illustrate one preferred embodiment of the presentlydisclosed surgical stapling device shown generally as 10. Briefly,surgical stapling device 10 includes a proximal handle assembly 12, anelongated central body portion 14 including a curved elongated outertube 14 a, and a distal head portion 16. Alternately, in some surgicalprocedures, e.g., the treatment of hemorrhoids, it is desirable to havea substantially straight, preferably shortened, central body portion.The length, shape and/or the diameter of body portion 14 and headportion 16 may also be varied to suit a particular surgical procedure.

Handle assembly 12 includes a stationary handle 18, a firing trigger 20,a rotatable approximation knob 22 and an indicator 24. Stationary handle18 is preferably formed from thermoplastic handle sections 18 a and 18b, e.g., polycarbonate, (FIG. 3) which together define a housing for theinternal components of handle assembly 12. Handle sections 18 a and 18 bare preferably secured together by sonic welding. Alternately, otherknown securement techniques may be employed including screws, adhesives,snap-fit connectors, etc. The internal components of handle portion 12will be discussed in detail below. Preferably, cushioned and/orresilient slip resistant portions such as a grip (not shown) can befastened to or included as part of handle sections 18 a and 18 b andfiring trigger 20. The slip resistant grip may be formed over handlesections 18 a and 18 b and firing trigger 20 using an overmoldingprocedure and may be formed from neoprene or rubber. Alternately, othersuitable materials, e.g., elastomeric materials, and joining techniquesmay be employed. A pivotally mounted trigger lock 26 is fastened tohandle assembly 12 and is manually positioned to prevent inadvertentfiring of stapling device 10. Indicator 24 is positioned on thestationary handle 18 and includes indicia, e.g., color coding,alpha-numeric labeling, etc., to identify to a surgeon whether thedevice is approximated and is ready to be fired. Indicator 24 preferablyhas a bulbous or convex shape which extends outwardly from a top surfaceof handle sections 18 a and 18 b and is easily viewable by a surgeonfrom the top and sides of the stapling device.

Head portion 16 includes an anvil assembly 30 and a shell assembly 31.Each of these assemblies will be discussed in detail below. Except whereotherwise noted, the components of surgical device 10 are generallyformed from thermoplastics including polycarbonates, and metalsincluding stainless steel and aluminum. The particular material selectedto form a particular component will depend upon the strengthrequirements of the particular component. For example, the anvil ispreferably formed from a metal, such as stainless steel, and thestationary handle is preferably formed from a thermoplastic such aspolycarbonate. Alternately, other materials not listed above, whichpreferably can withstand sterilization procedures, may be used to formcomponents of stapling device 10 provided the materials are suitable forsurgical use and meet the strength requirements of the particularcomponent.

FIGS. 3-5 illustrate the internal components of handle assembly 12. Theinternal components include the proximal components of approximation andfiring mechanisms, a firing lockout mechanism and an indicator drivemechanism. FIGS. 6 and 7 illustrate the internal components of elongatedbody portion 14. These components include the distal components of theapproximation and firing mechanisms. Each of these mechanisms will bedisclosed in detail hereinbelow.

Approximation Mechanism

Referring to FIGS. 3-8, the approximation mechanism includesapproximation knob 22, a drive screw 32, a rotatable sleeve 33, firstand second screw extensions 34 and 36 (FIG. 6), respectively, and ananvil retainer 38. Rotatable sleeve 33 includes a substantiallycylindrical hollow body portion 40 and a substantially cylindricalcollar 42 which together define a central bore 33 a. Collar 42 has anannular groove 44 formed thereabout which is dimensioned to receive aninwardly extending flange 46 formed on an inner wall of handle sections18 a and 18 b. Engagement between groove 44 and flanges 46 axially fixessleeve 33 within handle 18 while permitting rotation of sleeve 33 inrelation to stationary handle 18. The proximal end of body portion 40 ofrotatable sleeve 33 extends through an opening 18 b in the proximal endof stationary handle 18. A pair of diametrically opposed elongated ribs48 are positioned or formed on the outer surface of body portion 40.Approximation knob 22 includes a pair of internal slots 49 a positionedto receive ribs 48 of sleeve 33 to rotatably fix sleeve 33 to knob 22,such that rotation of knob 22 causes concurrent rotation of sleeve 33.

The proximal half of screw 32 includes a helical channel 50 and isdimensioned to be slidably positioned within central bore 33 a ofrotatable sleeve 33. The distal end of screw 32 includes an annularrecess 35 dimensioned to receive a seal member 37 (FIG. 3) for providinga fluid tight seal between the outer surface of screw 32 and the innersurface of pusher link 74. A pin 52 (FIG. 3) extends radially throughcylindrical collar 42 of sleeve 33 into helical channel 50. Since sleeve33 is axially fixed with respect to stationary handle 18, rotation ofsleeve 33 about screw 32 causes pin 52 to move along channel 50 of screw32 to effect axial movement of screw 32 within stationary handle 18. Inan alternate embodiment, helical channel 50 includes a dwell portion 50a (FIGS. 3′ and 3C). When pin 52 is positioned in dwell portion 50 a,the pitch of channel 50 is such that rotation of sleeve 33 effectssubstantially no axial movement of screw 32.

Referring to FIGS. 6-8, the distal end of screw 32 includes a transverseslot 54. Top and bottom screw extensions 34 and 36 (FIG. 6) each includea proximally located flexible flat band portion 58 and a distallylocated flat band portion 60. Alternately, it is envisioned that screwextensions 34 and 36 may have other than a band configuration. Forexample, screw extensions 34 and 36 may be semi-circular or circular incross-section. The flexibility of top and bottom screw extensions 34 and36 permits movement of screw extensions 34 and 36 through curvedelongated body portion 14. The proximal end of each band portion 58includes a hole 62 dimensioned to receive a pin 64 for securing theproximal end of screw extensions 34 and 36 within transverse slot 54 ofscrew 32. Alternately, other fastening techniques may be used to secureeach band portion 58 to screw 32, e.g., welding, crimping, etc. Distallylocated band portion 60 of each screw extension 34 and 36 is dimensionedto be received within a transverse slot 66 formed in a proximal end ofanvil retainer 38 (FIG. 7) to fasten anvil retainer 38 to the distal endof screw extensions 34 and 36. Preferably, a pair of pins 66 a whichextend through the proximal end of anvil retainer 38 and band portions60 are used to secure screw extensions 34 and 36 to anvil retainer 38.Alternately, band portions 60 can be brazed or welded within slot 66 orother fastening techniques may be used to secure band portions 60 ofscrew extensions 34 and 36 to anvil retainer 38, e.g., screws, crimping,etc. Anvil retainer 38 includes an annular protrusion 177 (FIG. 7) whichis configured to engage the anvil assembly in a manner to be discussedin detail below. Alternately, protrusion 177 need not be annular or mayinclude different attachment structure, e.g., recesses, grooves, etc.

Referring again to FIGS. 3-7, when approximation knob 22 is manuallyrotated, rotatable sleeve 33 is rotated about the proximal end of screw32 to move pin 52 along helical channel 50 of screw 32. Since sleeve 33is axially fixed to stationary handle 18, as pin 52 is moved throughchannel 50, screw 32 is advanced or retracted within stationary handle18 except when pin 52 is positioned within dwell 50 a. As a result, topand bottom screw extensions 34 and 36, which are fastened to the distalend of screw 32, and anvil retainer 38, which is fastened to the distalend of screw extensions 34 and 36, are moved axially within elongatedbody portion 14. Since anvil assembly 30 is secured to the distal end ofanvil retainer 38, rotation of approximation knob 22 will effectmovement of anvil assembly 30 in relation to shell assembly 31 betweenspaced and approximated positions. Dwell 50 a in channel 50 permitsabout ½ to ¾ of a turn of approximation knob 22 without any substantialaxial movement of screw 32 to identify to a surgeon that anvil assembly30 has been unapproximated a distance sufficient to allow tilting ofanvil head assembly 120 as will be discussed below. Dwell 50 a may alsobe positioned on screw 32 to provide an indicator to a surgeon thatanvil assembly 30 has been unapproximated a distance sufficient to allowremoval of anvil assembly 30 from anvil retainer 38 as will be discussedin further detail below.

Firing Mechanism

Referring to FIGS. 3-6 and 9, the firing mechanism includes firingtrigger 20, a firing link 72 and an elongated pusher link 74 (FIG. 6).Firing trigger 20 includes a body portion 76 and a trigger cover 80. Acushioned gripping surface (not shown) preferably formed of neoprene orrubber is provided on trigger cover 80. The cushioned gripping surfaceprovides a non-slip cushioned surface to make actuation of device 10more comfortable to a surgeon. The distal end of body portion 76 oftrigger 20 is pivotally connected to a coupling member 86 by a pivotmember 84. Coupling member 86 is secured to the proximal end of pusherlink 74 and may be formed integrally with pusher link 74 or as aseparate element fastened thereto. Firing link 72 has a distal endpivotally secured to body portion 76 of trigger 20 by a pivot member 87and a second end pivotally secured within a vertical slot 82 formedbetween stationary handle half-sections 18 a and 18 b of stationaryhandle 18 by pivot member 79. Pivot member 79 is free to move verticallywithin slot 82. A spring 82 a (FIG. 9) is supported within handle 18 tourge pivot member 79 downwardly towards the bottom of slot 82. Bodyportion 76 of trigger 20 further includes a pair of abutments includingan abutment 89 and an abutment 91 which are positioned to engage thedistal end 26 a (FIG. 4) of trigger lock 26 in a manner to be describedin greater detail below to prevent actuation of trigger 20 prior toapproximation of device 10.

Coupling member 86 which is supported on the proximal end of elongatedpusher link 74 includes a flange 104 (FIG. 6). A spring 106 ispositioned between a proximal end 15 of outer tube 14 a and flange 104(FIG. 4) to bias pusher link 74 proximally to a retracted, non-firedposition. A pair of wings 108 extend radially outwardly from couplingmember 86. Wings 108 are dimensioned to slide along channels 111 (FIG.3) formed along the internal walls of stationary handle 18 to maintainproper alignment of pusher link 74 within stationary handle 18 duringfiring of device 10.

Referring to FIG. 6, the distal end of pusher link 74 includes a pair ofengagement fingers 110 which are dimensioned to lockingly engage withmembers 220 formed in the proximal end of pusher back 186. Pusher back186 forms part of shell assembly 31 and will be discussed in greaterdetail below. Pusher link 74 is preferably formed from a flexibleplastic material and includes a plurality of notches 187 which allow thepusher link to bend more easily as it moves through body 14. Pusher link74 defines a hollow channel 75 for slidably receiving the approximationmechanism. A flat surface or cutout 74 a (FIG. 6) formed in pusher link74 slidably supports screw extensions 34 and 36 which are positioned injuxtaposed alignment. Spacers 77 are positioned within outer tube 14 aadjacent cutout 74 a to provide additional support for screw extensions34 and 36 and pusher link 74 to prevent each component from bucklingduring actuation. An annular channel 74 b is formed about pusher link 74to receive an 0-ring seal 74 c. Pusher link 74 is slidably positionedwithin body portion 14 such that O-ring 74 c seals the space betweenpusher link 74 and an internal wall of outer tube 14 a. Operation of thefiring mechanism of the device will be described in detail below.

Referring again to FIGS. 3-6 and 9, when firing trigger 20 is actuated,i.e., pivoted about pivot member 84, firing link 72 is moved proximallyuntil pivot member 79 engages an abutment surface 307 (FIG. 25A-D)formed on screw stop 306 (FIG. 3). Screw stop 306 is axially fixed toscrew 32 in a manner to be described in detail below. Thereafter, firingtrigger 20 is pushed distally to advance pusher link 74 distally againstthe bias of spring 106. Since the distal end of pusher link 74 isconnected to pusher back 186, actuation of firing trigger 20 effectsadvancement of pusher back 186 within shell assembly 31 to eject staplesfrom shell assembly 31 in a manner to be described below.

Anvil Assembly

Referring to FIGS. 10-21, anvil assembly 30 includes an anvil headassembly 120 and an anvil center rod assembly 152. Anvil head assembly120 includes a post 122, an anvil head 124, a backup plate 126, acutting ring 128, a retaining clip 127 and an anvil 129. Post 122 iscentrally positioned through a bore in anvil head 124. Alternately, post122 may be integrally formed with anvil head 124. Anvil 129 is supportedon anvil head 124 in an outer annular recess 136 and includes aplurality of pockets 140 for receiving and deforming staples. At leastone tab 129 a extends radially outwardly from anvil 129 and isdimensioned to be received within a cutout 124 a formed in anvil head124. Tab 129 a and cutout 124 a function to align anvil 129 withinannular recess 136. Backup plate 126 includes a central opening 126 bwhich is positioned about post 122 within an inner recess 134 of anvilhead 124 between post 122 and annular recess 136. Backup plate 126includes a raised platform 126 a. Cutting ring 128 includes an opening128 a having a configuration substantially the same as platform 126 a.Opening 128 a is positioned about platform 126 a to rotatably fixcutting ring 128 a on backup ring 126. Preferably, cutting ring 128 isformed from polyethylene and is fixedly secured to backup plate 126using, for example, an adhesive. Backup ring 126 is preferably formedfrom metal and provides support to cutting ring 128 to enhance thecutting of tissue. Alternately other materials of construction may beused to construct plate 126 and ring 128. Cutting ring 128 and backupplate 126 are slidably mounted about post 122. Backup plate 126 includesa pair of inwardly extending tabs 150 which will be described in furtherdetail below. Cutting ring 128 includes tabs 128 b which are receivedwithin cutouts 124 b formed in anvil head 124 to properly align backupring 126 and cutting ring 128 within anvil head 124.

Anvil center rod assembly 152 includes anvil center rod 154, a plunger156 and plunger spring 158. A first end of center rod 154 includes atransverse throughbore 160 which is offset from the central longitudinalaxis of center rod 154. Post 122 of anvil head assembly 120 alsoincludes a transverse throughbore 162. A pivot member 164 pivotablysecures post 122 to center rod 154 such that anvil head assembly 120 ispivotably mounted to anvil center rod assembly 152. Plunger 156 isslidably positioned in a bore 154 b (FIG. 16) formed in the first end ofcenter rod 154. Plunger 156 includes an engagement finger 168 which isoffset from the pivot axis of anvil head assembly 120 and biased intoengagement with the base 122 a of post 122 by plunger spring 158 to urgeanvil head assembly 120 to a pivoted position at an angle to center rod154. In a prefired untilted position, tabs 150 formed on backup plate126 engage a top surface 154 a (FIG. 20) of center rod 154 to preventanvil head assembly 120 from pivoting about pivot member 164. As device10 is fired, backup plate 126 and cutting ring 128 are moved deeper intoanvil recess 134 of anvil head 124 about post 122 (FIG. 21) by knife 188(FIG. 6) in a manner to be described in further detail below to movetabs 150 out of engagement with top surface 154 a of center rod 154 topermit plunger 156 to pivot anvil head assembly 120 about pivot member164.

A retainer clip 127 is positioned in a transverse slot 122 c formed inpost 122 and includes a pair of outwardly biased flexible arms 127 a and127 b. Arm 127 b includes a recess 127 c dimensioned to receive pivotpin 164 (FIG. 17). Prior to firing device 10, arms 127 a and 127 b aredeformed inwardly by backup plate 126 (FIG. 17). After device 10 hasbeen fired and backup plate 126 has been pushed deeper into anvil head124 by knife 188, flexible arms 127 a and 127 b spring outwardly to aposition in front of backup plate 126. In this position, arms 127 a and127 b prevent cutting ring 128 and backup plate 126 from sticking to theknife when anvil assembly 30 is unapproximated. It is envisioned that aretainer clip may be used in conjunction with non-pivotal anvilassemblies wherein the anvil head post and the anvil center rod areintegrally formed.

FIG. 11A illustrates an alternate embodiment of the retainer clip showngenerally as 127′. Retainer clip 127′ also includes a pair ofoutwardly-biased flexible arms 127 a′ and 127 b′. A circular bore 127 c′is provided to pivotably position clip 127′ about pivot pin 164 (FIG.17). Retainer clip 127′ differs from clip 127 in that clip 127′ includesa pair of tabs 127 d′ which are positioned to engage an inner surface ofbackup plate 126′ to prevent clip 127′ from rotating out of position toengage backup plate 126′ (See FIG. 16A).

A second end of center rod 154 includes a bore 170 defined by aplurality of flexible arms 155 a. Bore 170 is dimensioned to receive aremovable trocar 157. At least one of flexible arms 155, and preferablya plurality of flexible arms 155, e.g., three, include an opening 155 adimensioned to receive a projection 157 d formed on removable trocar 157to releasably secure trocar 157 to center rod 154 (FIG. 13). The distalends of each of flexible arms 155 include an internal shoulder 155 b(FIG. 10) dimensioned to releasably engage annular protrusion 177 ofanvil retainer 38. A plurality of splines 181 are formed about centerrod 154 and are dimensioned to be received within grooves 196 a (FIG. 6)in shell assembly 31 to align anvil assembly 30 within shell assembly 31during approximation of the anvil and shell assemblies. Center rod 154also includes an annular recessed portion 183 to facilitate grasping ofanvil assembly 30 by a surgeon with a grasper.

Referring to FIGS. 12 and 13, removable trocar 157 includes a trocar tip157 a, a body portion 157 b and a cantilevered arm 157 c. A projection157 d is positioned on the free end of cantilevered arm 157 c. Arm 157 cis deflectable downwardly, i.e., radially inwardly, in the directionindicated by arrow “A” in FIG. 13 to facilitate insertion of bodyportion 157 b into bore 170 of center rod 154. Splines 157 e or thelike, preferably, are provided on body portion 157 b to properly aligntrocar 157 within bore 170. Arm 157 c biases projection 157 d outwardlysuch that when projection 157 d passes beneath opening 155 a in centerrod 154, projection 157 d snaps outwardly into opening 155 a toreleasably secure removable trocar 157 to center rod 154. A tab 157 f ispositioned on arm 157 c and can be engaged to depress arm 157 c andprojection 157 d to remove projection 157 d from an opening 155 a of arm155 to facilitate removal of trocar 157 from center rod 154. Trocar tip157 a includes a throughbore 157 g dimensioned to receive a suture (notshown) to facilitate locating and removal of trocar 157 and/or anvilassembly 30 within and from the human body. Although illustrated ashaving a sharpened tip, other trocar tip configurations are envisioned,e.g., a blunt tip.

FIG. 13A illustrates an alternate embodiment of the trocar showngenerally as 157′. Trocar 157′ differs from trocar 157 in that itfurther includes an elongated rib 157 h′ which is dimensioned to slidebetween arms 155 (FIG. 12) of center rod 154. Rib 157 h′ ensuresalignment of projection 157 d′ with openings 155 a (FIG. 12) of arms155. Projection 157 d′ also includes a tapered or angled face 157 i′.

Shell Assembly

Referring to FIG. 6, shell assembly 31 includes a shell 182, a pusherback 186, a cylindrical knife 188, and a staple guide 192. Shell 182includes an outer housing portion 194 and an inner guide portion 196having grooves 196 a for mating with splines 181 on anvil center rod 154(FIG. 10). Outer housing portion 194 defines a throughbore 198 having adistal cylindrical section 200, a central conical section 202 and aproximal smaller diameter cylindrical section 204. A plurality ofopenings 206 are formed in conical section 202. Openings 206 aredimensioned to permit fluid and tissue passage during operation of thedevice. A pair of diametrically opposed flexible engagement members 207are formed on proximal cylindrical section 204 of shell 182. Engagementmembers 207 are positioned to be received in openings 207 a formed onthe distal end of outer tube 14 a to secure shell 182 to elongated body14. A pair of openings 211 formed in the proximal end of outer tube 14 aare dimensioned to receive protrusions (not shown) formed on theinternal wall of stationary handle 18 to facilitate attachment of tube14 a to handle portion 12.

Pusher back 186 includes a central throughbore 208 which is slidablypositioned about inner guide portion 196 of shell 182. Pusher back 186includes a distal cylindrical section 210 which is slidably positionedwithin distal cylindrical section 200 of shell 182, a central conicalsection 212 and a proximal smaller diameter cylindrical section 214. Theproximal end of pusher back 186 includes members 220 which areconfigured to lockingly engage with resilient fingers 110 of pusher link74 to fasten pusher link 74 to pusher back 186 such that a distal faceof pusher link 74 abuts a proximal face of pusher back 186.

The distal end of pusher back 186 includes a pusher 190. Pusher 190includes a multiplicity of distally extending fingers 226 dimensioned tobe slidably received within slots 228 formed in staple guide 192 toeject staples 230 therefrom. Cylindrical knife 188 is frictionallyretained within the central throughbore of pusher back 186 to fixedlysecure knife 188 in relation to pusher 190. Alternately, knife 188 maybe retained within pusher back 186 using adhesives, crimping, pins, etc.The distal end of knife 188 includes a circular cutting edge 234.

In operation, when pusher link 74 is advanced distally in response toactuation of firing trigger 20, as will be described below, pusher back186 is advanced distally within shell 182. Advancement of pusher back186 advances fingers 226 through slots 228 of staple guide 192 toadvance staples 230 positioned within slots 228 and eject staples 230from staple guide 192 into staple deforming pockets 140 of anvil 129.Since knife 188 is secured to pusher back 186, knife 188 is alsoadvanced distally to core tissue as will be described in more detailbelow.

A rigid bushing 209 is supported in the proximal end of inner guideportion 196 of shell 182. Bushing 209 defines a throughbore dimensionedto slidably receive anvil retainer 38 and center rod 154 of anvilassembly 30 (FIG. 14). Bushing 209 provides lateral support for flexiblearms 155 of center rod 154 when the anvil assembly 30 has beenapproximated to prevent disengagement of anvil assembly 30 from anvilretainer 38. More specifically, when flexible arms 155 are positionedwithin bushing 209, bushing 209 prevents flexible arms 155 of center rod154 of anvil assembly 30 from flexing outwardly to prevent disengagementof anvil assembly 30 from annular rib 177 of anvil retainer 38. In theunapproximated position, flexible arms 155 of center rod 154 arepositioned externally of bushing 209 to permit removal of anvil assembly30 from retainer 38.

As discussed above, dwell 50 a in channel 50 of screw 32 can be locatedon screw 32 to provide an indication to a surgeon that the anvilassembly 30 has been unapproximated a distance sufficient to allowremoval of anvil assembly 30 from anvil retainer 38 or, alternatively,that any further unapproximation of anvil assembly 30 will move anvilassembly 30 to a position in which anvil assembly 30 can be disengagedfrom anvil retainer 38. As such, when a surgeon is rotatingapproximation knob 22 to unapproximate anvil assembly 30 and shellassembly 31, a tactile indication is provided to the surgeon by dwell 50a in channel 50 of screw 52 to indicate to the surgeon that anvilassembly has been unapproximated to one of the positions describedabove.

Cam Adjustment Mechanism

Referring to FIGS. 8 and 22-28, a cam adjustment member 400 is securedby set screw 312 onto a sidewall 306 a of screw stop 306 within a recess306 b formed in sidewall 306 a. Cam adjustment member 400 includes acircular disc 402 having a throughbore 404. Throughbore 404 iseccentrically formed through disc 402 and is dimensioned to receive setscrew 312. A smaller notch or hole 406 is also formed in disc 402 and isdimensioned to receive the tip of an adjustment tool (not shown). Recess306 b (FIG. 22) includes a forward abutment shoulder or surface 306 cand a rear abutment surface 306 d and is dimensioned to receive disc 402such that the outer edge of disc 402 abuts forward and rear abutmentsurfaces 306 c and 306 d.

Set screw 312 extends through disc 402 and screw stop 306 and isreceived in a threaded bore 32 a (FIG. 6) in screw 32 to secure screwstop 306 in an axially fixed position on screw 32. Cam adjustment member400 functions to adjust the axial position of screw stop 306 on screw32. More specifically, set screw 312 can be loosened to allow disc 402to rotate within recess 306 b of screw stop 306. Since disc 402 iseccentrically mounted about screw 32 and engages forward and rearabutment surfaces 306 c and 306 d of recess 306 b, rotation of disc 402about fixed set screw 312 will urge screw stop 306 axially along screw32 to adjust the axial position of screw stop 306 on screw 32. Forexample, when disc 402 is rotated in a clockwise direction (as viewed inFIG. 28) as indicated by arrow “B”, screw stop 306 will be moved axiallyin relation to screw 32 in the direction indicated by arrow “C” inresponse to engagement between the outer edge of disc 402 and rearshoulder 306 d of recess 306 b. Conversely, when disc 402 is rotated ina counter-clockwise direction (as viewed in FIG. 27), as indicated byarrow “D”, screw stop 306 will be moved axially in relation to screw 32in the direction indicated by arrow “E” in response to engagementbetween the outer edge of disc 402 and forward shoulder 306 c of recess306 b.

When stapling device 10 is in a fully approximated position, i.e., anvilassembly 30 and shell assembly 31 are brought into juxtaposed alignmentto define a tissue receiving clearance (FIG. 46), screw stop 306 abutsagainst body portion 42 of the rotatable sleeve 33, i.e., sleeve 33functions as a stop for the approximation mechanism. See FIG. 48. Inthis position, anvil assembly 30 and shell assembly 31 are spacedslightly to define a tissue receiving clearance. By providing camadjustment member 400, the tissue receiving clearance can be selectivelyadjusted to be within a desired range by adjusting the position of screwstop 306 on screw 32. Preferably, cam adjustment member 400 permitsadjustment of the tissue receiving clearance of ±0.045 inches, althoughgreater or lesser adjustment capabilities are also envisioned.Typically, adjustments to the tissue receiving clearance will be made bythe device manufacturer. Alternately, a hole or opening may be providedin handle portion 12 (FIG. 1) to provide direct access to adjustmentmember 400 to allow for on-site adjustment of the tissue receivingclearance by a surgeon or other medical professional.

Indicator Mechanism

Referring to FIGS. 3-5 and 29, the indicator mechanism includes bulbousindicator 24, lens cover 24 a and slide member 500. Indicator 24 ispivotally supported about a pivot member 502 which is preferably formedmonolithically with handle sections 18 a and 18 b. Lens cover 24 a ispositioned above indicator 24 and is preferably formed of magnificationmaterial to facilitate easy visualization of indicator 24. Slide member500 includes a body portion 504 having a elongated slot 506 formedtherein, a distal abutment member or upturned lip portion 508, and aproximal extension 510. Slide member 500 is slidably positioned betweenhandle sections 18 a and 18 b. Proximal extension 510 is slidablysupported within stationary handle 18 by support structure 516 (FIG. 5)which may be integrally formed with handle sections 18 a and 18 b. Abiasing member, preferably a coil spring 512, is positioned incompression about proximal extension 510 between support structure 516and body portion 504 of slide member 500 to urge slide member 500distally within stationary handle 18. Indicator 24 includes a pair ofdownwardly extending projections 518 and 520 (FIG. 32). Upturned lipportion 508 of slide member 500 is positioned between projections 518and 520 and is positioned to engage projections 518 and 520 as it moveswithin stationary handle 18. In the unfired position of device 10,biasing member 512 urges slide member 500 distally to move lip portion508 into engagement with projection 518 to pivot indicator to a firstposition, which provides indication to a surgeon that the device has notbeen approximated and is not in a fire-ready condition.

As discussed above, screw stop 306 is fixedly attached to screw 32 (FIG.33). Screw stop 306 includes a first abutment or engagement member 522which is positioned to travel through slot 506 of slide member 500 andengage the proximal end 506 a (FIG. 29) of slot 506 during approximationof the device. When engagement member 522 abuts proximal end 506 a ofslot 506, further approximation of device 10 moves slide plate 500proximally within stationary handle 18 against the bias of spring 512such that upturned lip 508 of slide member 500 engages projection 520 ofindicator 24. Engagement between projection 520 and lip 508 causesindicator 24 to pivot about pivot member 502 to a second position. Inthe second position, indicator 24 provides indication to a surgeon thatthe device has been approximated and is now in a fire-ready position.See FIG. 48.

Fire-Lockout Mechanism

Referring to FIGS. 3-5, and 30, the firing-lockout mechanism includestrigger lock 26 and a lockout member 530. Trigger lock 26 is pivotallysupported within bores 532 (FIG. 3) in handle sections 18 a and 18 babout pivot member 534. Pivot member 534 is preferably T-shaped andfrictionally engages the inner wall of bores 532 to prevent freerotation of trigger lock 26. Alternately, other pivot memberconfigurations are envisioned, e.g., circular, square, etc. Tip 26 a oftrigger lock 26 is positioned between abutments 89 and 91 on bodyportion 76 of firing trigger 20 to prevent actuation of trigger 20 whentrigger lock 26 is in the locked position. Trigger lock 26 also includesa proximal extension 26 b which will be discussed in further detailbelow.

Referring also to FIG. 3B, an alternate embodiment of the trigger lockis shown generally as 26′. Trigger lock 26′ includes a flexibleextension or tab 26 b′ which extends outwardly from tip 26 a′. Extension26 b′ is dimensioned to engage the space between abutments 89 and 91 toprevent rattling of trigger lock 25′ between abutments 89 and 91.Flexible extension 26 b′ is deformable to facilitate passage overabutment 91.

Lockout member 530 includes a body portion 536, a proximal extension538, a pair of front legs 540 a, a pair of rear legs 540 b, and anabutment member or downturned lip portion 542. Lockout member 530 isslidably positioned between first and second stops 544 and 546 (FIG. 5)formed on an internal wall of handle sections 18 a and 18 b. Stop 544 ispositioned to engage rear legs 540 b and stop 546 is positioned toengage front legs 540 a. It is also envisioned that a single abutmentmember may be substituted for each pair of legs. A biasing member,preferably a coil spring 549, is positioned between stop 544 and body536 about proximal extension 538 to urge lockout 530 to its distal-mostposition with legs 540 abutting stop 546. In this position, extension 26b of trigger lock 26 is positioned beneath lip portion 542 of lockoutmember 530 to prevent pivotal movement of trigger lock 26 about pivotmember 534, and thus prevent firing of stapling device 10.

As discussed above, screw stop 306 is secured to screw 32. A secondengagement member or members 548 extend downwardly from screw stop 306(FIG. 23). When stapling device 10 is approximated and screw 32 is movedproximally within stationary handle 18, engagement member 548 abutsdistal legs 540 a (FIG. 47) of lockout member 530 to move lockout member530 proximally against the bias of spring member 549 to a position inwhich lip portion 542 is spaced proximally of extension 26 b of triggerlock 26. In this position of lockout member 530, trigger lock 526 can bepivoted about pivot member 534 to permit firing of stapling device 10.

Tactile Indicator Mechanism

Referring to FIGS. 3, 5, 9 and 9A, a tactile indicator mechanismprovided in stationary handle 18 includes an abutment member 580 whichis slidably positioned in a vertical slot 582 defined within handlesections 18 a and 18 b. Abutment member 580 includes a protuberance 580a and a guide rib 580 b. Protuberance 580 a is dimensioned to bereceived within one of two detents 582 a and 582 b formed along a wallof slot 582. Abutment member 580 is movable from a retracted (downward)position, wherein protuberance 580 a is positioned within detent 582 a,to an extended (upward) position, wherein protuberance 580 a ispositioned within detent 582 b. Engagement between protuberance 580 aand detents 582 a and 582 b retains abutment member 580 in itsrespective upward or downward position.

Prior to firing of stapling device 10, abutment member 580 is located inthe retracted (downward) position. When device 10 is fired, an extension590 (FIG. 3) of firing link 72 engages abutment member 580 and movesabutment member 580 from its retracted to its extended position. In theextended position, abutment member 580 extends into channel 111 ofstationary handle 18.

Screw stop 306 includes a pair of wings 584 which are slidablypositioned in channel 111 of stationary handle 18. After stapling device10 has been fired, abutment member 580 is positioned within channel 111.During unapproximation of anvil assembly 30 and cartridge assembly 31, awing 584 of screw stop 306 will engage abutment member 580 and urgeabutment member 580 back to its retracted (downward) position.Engagement between abutment member 580 and wing 584 of screw stop 306provides a tactile and/or an audible indication to the surgeon that theanvil and cartridge assemblies 30 and 31 have been unapproximated apredetermined amount. Preferably, abutment member 580 is positioned toengage wing 584 of screw stop 306 at the point when the anvil andcartridge assemblies have been separated a distance sufficient to allowthe anvil head assembly to tilt. Thus, engagement between abutmentmember 580 and wing 584 of screw stop 306 provides a tactile and/oraudible indication to the surgeon that the anvil head assembly 120 hastilted and stapling device 10 can be removed from a patient.

Operation

Operation of surgical stapling device 10 will now be described in detailwith reference to FIGS. 31-61.

FIGS. 31-35 illustrate surgical stapling device 10 in the unapproximatedor open position prior to attachment of anvil assembly 30 to anvilretainer 38. In this position, biasing member 106 (FIG. 33) is engagedwith coupling 86 to urge pusher link 74 to its proximal-most position inwhich coupling 86 abuts screw-stop 306. Biasing member 512 is engagedwith slide member 500 of the indicator mechanism to position slidemember 500 in engagement with projection 518 of indicator 24 to pivotindicator 24 in a clockwise direction, as viewed in FIG. 33. Biasingmember 549 is engaged with body 536 of lockout member 530 to urgelockout member 530 to its distal-most position, wherein lip portion 542of lockout member 530 is positioned above extension 26 b of trigger lock26 to prevent movement of trigger lock 26 to the unlocked position.Biasing member 82 a is also engaged with pivot member 79 (FIG. 32) tourge pivot member 79 to the base of vertical slot 82 and tactileindicator 580 is in the retracted or downward position with protrusion580 a positioned with detent 582 a.

FIGS. 36-44 illustrate surgical stapling device 10 with anvil assembly30 attached to anvil retainer 38 and the anvil assembly 30 in theunapproximated or open position. Referring to FIGS. 37 and 38, duringattachment of anvil assembly 30 to anvil retainer 38, anvil retainer 38is positioned within bore 170 of center rod 154 of anvil assembly 30.Flexible arms 155 deflect outwardly to accommodate center rod 154.Center rod 154 is advanced onto anvil retainer 38 in the directionindicated by arrow “K” in FIG. 37 until internal shoulder 155 b offlexible arms 155 passes over annular protrusion 177 formed on anvilretainer 38. At this point, resilient legs 155 releasably engage theanvil retainer. The position of the remaining components of staplingdevice are not affected by attachment of anvil assembly 30 to anvilretainer 38 and remain as described above and shown in FIGS. 31-35.

FIGS. 45-50 illustrate surgical stapling device 10 during movement ofanvil assembly 30 and cartridge assembly 31 to the approximated orclosed position. As discussed above, anvil assembly 30 is moved to theapproximated or closed position by rotating rotation knob 22 in thedirection indicated by arrow “L” in FIG. 45. Rotation of knob 22 causescylindrical sleeve 33 to rotate to move pin 52 along helical channel 50of screw 32. See FIG. 48. Movement of pin 52 along helical channel 50causes screw 32 to translate proximally within sleeve 33. The distal endof screw 32 is connected to screw extensions 34 and 36 which arefastened at their distal ends to anvil retainer 38 (FIG. 46). As such,retraction of screw 32 within sleeve 33 is translated into proximalmovement of anvil retainer 38 and anvil assembly 30. It is noted thatwhen anvil assembly 30 is approximated, flexible legs 155 of center rod154 are drawn into bushing 209 to lock legs 155 onto anvil retainer 38.

Referring to FIGS. 47-49, screw stop 306 is axially fixed to screw 32 byset screw 312. Thus, as screw 32 is retracted within sleeve 33, screwstop 306 is moved from a distal position within stationary handle 18 toa proximal position. As screw stop 306 moves from the distal position tothe proximal position, first engagement member 522 formed on screw stop306 abuts proximal end 506 a of slot 506 of slide plate 500 (FIG. 29)and moves slide plate 500 proximally against the bias of spring 512. Asslide plate 500 moves proximally, lip 508 (FIG. 48) of slide member 500engages projection 520 of indicator 24 to pivot indicator 24 in acounter-clockwise direction as viewed in FIG. 48.

Screw stop 306 also includes a second engagement member 548 (FIG. 47).As screw stop 306 is moved from the distal position to the proximalposition during approximation of anvil assembly 30, second engagementmember 548 engages distal legs 540 a of lockout member 530 to movelockout member 530 proximally to a position in which lip portion 542 isspaced proximally of extension 26 b of trigger lock 26. In thisposition, trigger lock 26 can be pivoted to an unlocked position topermit firing of stapling device 10.

Movement of screw stop 306 to its proximal-most position withinstationary handle 18 positions abutment surface 307 of screw stop 306 inposition to engage pivot member 79 of firing link 72. Abutment surface307 comprises a substantially concave surface which is positioned topartially capture and act as a backstop for pivot 79 during firing ofthe stapling device.

FIGS. 51-56 illustrate surgical stapling device 10 during the firingstroke of firing trigger 20. As trigger 20 is compressed towardsstationary handle 18 in the direction indicated by arrow “M” in FIG. 52,pivot member 79 engages abutment surface 307 on screw stop 306 andfiring trigger 20 is pushed distally. As discussed above, the distal endof firing trigger 22 is connected through coupling member 86 to theproximal end of pusher link 74. Accordingly, as firing trigger 20 ismoved distally, pusher link 74 is moved distally in the directionindicated by arrow “N” in FIG. 52 to effect advancement of pusher back186 within shell assembly 31 (FIG. 52). Fingers 190 of pusher back 186engage and eject staples 230 from staple guide 192.

Cylindrical knife 188 is moved concurrently with pusher back 186 suchthat knife 188 moves into engagement with cutting ring 128 and backupplate 126. As discussed above, cutting ring 128 is preferably formedfrom polyethylene and backup plate 126 is preferably formed from metal.When knife 188 engages cutting ring 128, it cuts into cutting ring 128and pushes backup plate 126 deeper into anvil head 124 to move tabs 150(FIG. 56) from engagement with top surface 154 a of center rod 154 (FIG.56). Anvil head 124 is now free to pivot about member 164 and is urgedto do so by plunger 156. It is noted that because the anvil assembly isin juxtaposed alignment with shell assembly 31, the anvil head 14 willnot pivot fully until the anvil and shell assemblies have beenunapproximated a distance sufficient to allow the anvil head to fullypivot. When backup plate 126 moves into anvil head 124, flexible arms127 a and 127 b of retainer clip 127 (FIG. 55) spring outwardly to aposition in front of backup plate 126 blocking movement of backup plate126 out of anvil head 124. As discussed above, arms 127 a and 127 bprevent backup plate 126 from sticking to knife 188 when anvil assembly30 is returned to the unapproximated position.

Referring to FIGS. 53 and 54, as trigger 20 is actuated, i.e.,compressed towards stationary handle 18, extension 590 of firing link 72is pivoted towards and engages abutment member 580 to move abutmentmember 580 from its retracted to its extended position. In its extendedposition, abutment member obstructs channel 111 of stationary handle 18.

Referring to FIGS. 57-60, during unapproximation of stapling device 10after device 10 has been fired, wing 584 of screw stop 306 engagestactile indicator 580 (FIG. 58) at the point of unapproximation at whichanvil head 124 is able to pivot to the tilted reduced profile position.Contact between wing 584 and tactile indicator 580 provides a tactileand/or audible indication that anvil head 124 has tilted. If additionalforce is provided to approximation knob 22, wing 584 of screw stop 306will force tactile indicator to the retracted position to allow staplingdevice 10 to move to the fully open position. In this position, flexiblearms 155 are positioned distally of bushing 209 and anvil assembly 30can be disengaged from anvil retainer 28.

It will be understood that various modifications may be made to theembodiments disclosed herein. Therefore, the above description shouldnot be construed as limiting, but merely as exemplifications ofpreferred embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.For example, although the description refers exclusively to staples, itis envisioned that staples may include different types of tissuefasteners including two-part fasteners. In a stapling device forapplying two-part fastener, the anvil assembly of the stapling devicewould support one part of each two-part fastener.

What is claimed is:
 1. A removable trocar comprising: a body having aproximal end and a distal end, a trocar tip formed at the distal end ofthe body, a cantilevered arm extending along a longitudinal axis of thebody, the cantilevered arm including a distal end secured to the bodyand a proximal end having a protrusion formed thereon, the protrusionbeing dimensioned to be releasably received within an opening of ananvil center rod, and a rib extending proximally of the protrusion, therib being dimensioned to slide between flexible arms of an anvil centerrod to properly align the projection with the opening of the anvilcenter rod.
 2. A removable trocar according to claim 1, wherein theprojection includes an angled proximal face.
 3. A removable trocaraccording to claim 1, wherein the cantilevered arm includes a distaltab, the distal tab being positioned to facilitate deflection of thecantilevered arm to disengage the projection from an anvil center rod.4. A removable trocar according to claim 1, further including at leastone spline offset from the rib.
 5. A removable trocar according to claim1, further including a throughbore formed through the body, thethroughbore being dimensioned to receive a suture.